1. Technical Field
The present disclosure relates to a liquid crystal display (LCD) and, more particularly, to an LCD driver including a test pattern generating circuit.
2. Discussion of Related Art
A liquid crystal display (LCD) is compact and has a low power consumption compared to other display devices. The LCD is used in various electronic devices, such as notebook computers and mobile phones. In particular, an active matrix type LCD using a thin film transistor as a switching element is suitable for displaying moving images.
FIG. 1 is a block diagram of a conventional system 100 for driving an LCD panel. Referring to FIG. 1, the system 10 includes an LCD panel 110, a driver 120, a CPU interface 170 and a central processing unit (CPU) 180. The CPU 180 is also referred to as a baseband processor.
The driver 120 is directly interfaced to the CPU 180 through the CPU interface 170 and receives image data, for example, R (Red), G (Green) and B (Blue) digital video data, and a control signal from the CPU 180. The driver 120 using the CPU interface 170 may be used in a mobile communication device (or mobile set), such as a cellular phone.
To reduce the access load of the CPU 180 directly communicating with the driver 120 and to support various images, a graphic processor (not shown) may be connected between the driver 120 and the CPU 180. The graphic processor is coupled to the driver 120 through a video interface (or RGB interface) and to the CPU 180 through the CPU interface 170.
The driver 120 includes a timing controller 130, a gate driver circuit 150 and a source driver circuit 160. The timing controller 130 receives the image data and the control signal output from the CPU 180 through the CPU interface 170 and generates a control signal for controlling the operation timing of the gate driver circuit 150 and the source driver circuit 160.
The timing controller 130 includes a memory 140. The memory 140 stores the image data output from the CPU 180 through the CPU interface 170. The memory 140 may be configured using a graphic RAM. The image data stored in the memory 140 is output to the source driver circuit 160 under the control of the timing controller 130.
The gate driver circuit 150 includes a plurality of gate drivers (not shown) and drives gate lines (or scan lines) G1, G2, through to GM of the LCD panel 110 in response to the control signal output from the timing controller 130. The source driver circuit 160 includes a plurality of source drivers (not shown) and drives source lines (or data lines) S1, S2, through to SN of the LCD panel 110 in response to the image data output from the memory 140 and the control signal output from the timing controller 130.
The LCD panel 110 displays an image corresponding to the image data output from the CPU 180 in response to the signals output from the gate driver circuit 150 and the signals output from the source driver circuit 160.
To test an LCD (or LCD module) including the LCD panel 110 and the driver 120, the driver 120 receives signals, including test image data that constructs various test image patterns from a separate external test device (not shown) and controls the received test image patterns to be displayed on the LCD panel 110.
The test of the LCD includes a visual quality test and a test of the reliability of the LCD panel 110. The test image patterns are applied to the LCD panel 110 to check whether the test image patterns, such as a gray pattern, a cross-talk pattern and a flicker pattern, are correctly displayed.
As described above, the conventional driver 120 receives signals required for generating test image patterns from the external test device. Thus, interface conditions of the driver 120 and the external test device must be considered. Accordingly, a test for an LCD employing the conventional driver 120 is complicated and requires a long test time.